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2 18                        '      SKULL OF ELEPHANT                            CHAP,

JSlephas alone survives. This genus also includes many extinct
forms, both American and European, as well as Asiatic and
African. The entirely extinct genera are Stegodon and Mastodon.
The group is clearly one dwindling towards extermination. From
the Middle Miocene downwards these great " pachyderms " have
existed; and from the Miocene up to Pleistocene times they were
almost world-wide in range and numerous in species.

The genus Eleplias comprises usually large, but occasionally
(the pygmy Elephant of Malta) quite small forms. The external
features of the genus differ slightly in different species,, and will
therefore be described in relation to those species which we shall
notice here. The vertebral formula is C 7, D 19-20, L 3-5,
Sa 4-5, Ca 24-30, or even more.

The bodies of the vertebrae are remarkable for their shortness
and for the very flattened articular surfaces.

The skull is large and massive. Its large and heavy character
is, as has been stated in the definition of the sub-order, due to the

FIG. 116.A section of the cranium of a full-grown African Elephant, taken to the left
of the middle line, and including the vomer ( Fo) and the mesethmoid (JfJS) ; an,
anterior, and jw, posterior narial aperture. x ^. (From Flower's Osteology.)
immense development of air cavities in the diploe; the diameter
of the wall of the skull is actually greater than that of the
cranial cavity. These cavities are not obvious in the young
animal. They are most conspicuous in the roofing bones of
the skull, but are seen elsewhere, and thicken the basis cranii,